ArrayReadWriteBenchmark.cs

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Configs;
using BenchmarkDotNet.Jobs;
using Random = System.Random;

namespace Storage.Benchmark;

[SimpleJob(RuntimeMoniker.Net60)]
[SimpleJob(RuntimeMoniker.NetCoreApp31)]
[SimpleJob(RuntimeMoniker.Net48)]
[CategoriesColumn, MeanColumn]
[GroupBenchmarksBy(BenchmarkLogicalGroupRule.ByJob)]
public class ArrayReadWriteBenchmark
{
    [Benchmark]
    public int ForeachCustom()
    {
        var sum = 0;
        foreach (ref var element in new ArrayEnumerator<int>(_array))
        {
            sum += element;
            element = sum;
        }

        return sum;
    }

    [Benchmark(Baseline = true)]
    public int ForeachSpan()
    {
        var sum = 0;
        foreach (ref var element in _array.AsSpan())
        {
            sum += element;
            element = sum;
        }

        return sum;
    }

    [Benchmark]
    public int Reference()
    {
        var sum = 0;
        for (var i = 0; i < _array.Length; i++)
        {
            ref var element = ref _array[i];
            sum += element;
            element = sum;
        }

        return sum;
    }

    [Benchmark]
    public int Terrible()
    {
        var sum = 0;
        for (var i = 0; i < _array.Length; i++)
        {
            sum += _array[i];
            _array[i] = sum;
        }

        return sum;
    }

    [Benchmark]
    public unsafe int Unsafe()
    {
        var length = _array.Length;
        var sum = 0;
        fixed (int* arrayPtr = &_array[0])
        {
            // ReSharper disable once TooWideLocalVariableScope
            int* elementPtr;
            for (var i = 0; i < length; i++)
            {
                elementPtr = arrayPtr + i;
                sum += *elementPtr;
                *elementPtr = sum;
            }
        }

        return sum;
    }

    #region Configuration

    private int[] _array = null!;

    [GlobalSetup]
    public void Init()
    {
        const int count = 1021;
        
        _array = new int[count];

        var rnd = new Random(1234);
        for (var i = 0; i < count; i++)
        {
            _array[i] = rnd.Next(0, 10);
        }
    }

    #endregion
}